


Spiritual Summation, then Division

by LoveThyFrenemies



Category: Harry Potter - J. K. Rowling
Genre: Alternate Universe - Harry Potter Setting, Gen, Sirius Black Raises Harry Potter, Soul Twin, Well-Meaning Albus Dumbledore
Language: English
Status: In-Progress
Published: 2019-09-22
Updated: 2019-09-22
Packaged: 2020-10-25 19:10:14
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,749
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20729306
Author URL: https://archiveofourown.org/users/LoveThyFrenemies/pseuds/LoveThyFrenemies
Summary: Sirius would do absolutely anything to protect his godson, even if it means burying his past and fleeing the Britain. Unfortunately, the fate isn't generous enough to let them go. After all, he is stuck with Harry's 'twin' that has Voldemort's soul.





	Spiritual Summation, then Division

_ Please, please, please let me be wrong, Merlin- _

Sirius stumbled over a rock and tripped on the rugged ground. His palms and knees got bruised and cut, but he immediately sprung up and kept running. It should have been a perfect plan to ambush Voldemort; Voldemort was supposed to come for Sirius at his own place that he leaked to Death Eaters, but he instinctively knew that something was amiss when nobody even came within twenty meters of his house all night. Unless Voldemort suddenly changed his plans, it only meant that the Fidelius charm failed and.  Sirius felt the blood drain from his face as a feeling of dread washed over him as he saw the smoke coming from the distance, undoubtedly from the house that Potters used as a hideout, confirming his worst fear.

_ Peter sold out the Potters. _

Smoke and dust poured out of the house as Sirius blew the entrance door away with a blasting spell. His eyes teared up at the sight of a dead body.

“James!” Sirius futilely called his best friend’s name. He knelt on the floor and shook him, but James’ blank eyes and nonexistent puls didn’t change. Tears welled up in his eyes, but he wiped them away and ran upstairs to where Harry was supposed to be.

The room was in shambles with a broken door, damaged wall and ceilings all showing traces of spell explosion. As he saw Lily sprawled out on the floor, he felt his last thread of hope slipping through his hands.

His hands trembled, and he plopped on the floor as his legs went lax from defeat and shock. Salty droplets streamed relentlessly over his face and dropped on the wooden floor. The guilt on his shoulders as he regretted his decision to change the Secret Keeper at the last minute flooded his emotions.

_ “PETER!” _

Sirius roared. The anger and sadness from the betrayal and friends’ death turned to hate, and it quickly brewed and dominated Sirius’ mind. He was always a reckless one, and he was one step away from sprinting outside the house to find that motherfucker and kill him. That coward had to pay-

“Wah!”

A short cry diverted Sirius’ attention. He saw a crib on the opposite side of the room and immediately ran to it. As if gods had answered his hope, there was Harry, looking up at Sirius with a smiling face like a cherub. This time, tears of relief and joy blurred his vision, and he was about to raise Harry…

…until he saw another baby next to Harry.

_ What on earth…? _

Harry happily smiled and poked the baby who was calmly sitting next to him. A carbon copy of Harry was staring back at Sirius with same green eyes that Harry had. When did James have twins?

“Who’s this, Harry?”

Sirius felt stupid asking a baby who couldn’t even form a simple word, but Harry seemed to understand that Sirius was referring to a mysterious baby and simply hugged the other. The baby didn’t seem to mind the hug, but he keenly stared at Sirius, causing goose-bumps on his skin. Unlike beautiful depth of green that Harry possessed, the other’s eyes seemed to reflect a bottomless pit of green, dark, eerie abyss that made him want to look away, as if there was something else beyond those eyes that peered into Sirius’ soul. 

_ Poof! _

“Kreacher?!” Sirius gaped at the disgruntled house-elf that he hadn’t seen or heard for years. An ugly, scrawny house-elf stood on the edge of the crib.

_ “ _ Master Regulus would like me to protect a bastard son like you and whatever these abominations may be, _ ” _ Kreacher spat with hateful eyes at Sirius.

“My idiot Death Eater brother?” Sirius gaped even further, “I thought he died! Where is he, and what does he want? I am not going anywhere-“

“Master Regulus’ orders supersede whatever you utter!”

Kreacher snapped his finger, and the space around them distorted into singular point of compressed space. After momentary unpleasant squeezes and stretches, Sirius landed on the dusty, dark floor. He quickly looked around the new environment and recognized that it was the attic of his birth house that he detested. The crib with the babies landed gracefully with Kreacher, and Harry giggled.

Kreacher didn’t give Sirius a moment to recover and snapped his finger again. Over twenty knives and spears aimed at Sirius’ neck, stopping Sirius’ resistance preemptively. “What the  _ fuck _ is going on, Kreacher?”

“Master Regulus left a will just for you,” Kreacher croaked, “just to save your worthless life and your damned fate from a prophecy! You should be honored! Not even the mistress knows you are here, so shut up!”

“What prophecy?” Sirius dumbly asked. His idiot brother wanted to save him? From what?

Kreacher clapped toward a corner of the room. A silver basin with series of runes flew to him and landed on an old wooden table.

_ We had a Pensieve?  _ Sirius whistled, mildly impressed. Kreacher summoned a vial that contained silvery substance and poured it into the basin.

“Get in!”

Kreacher levitated Sirius and hauled him in to the Pensieve. Sirius flung a string of the worst insults that he could possibly think of to Kreacher as he fell into depths of someone’s memory. He vowed that wretched thing would pay if he did something to Harry.

His feet slowly landed on a plain, clean but old hallway. He immediately knew that this was Hog’s Head based on its nondescript appearance. It seemed like an ordinary day with not many few customers, but his eyes widened when he saw Dumbledore and a woman coming from the opposite direction. The woman wore a pair of goofy glasses and had unkempt, frizzly hair, and seemed excited while Dumbledore had his usual jovial countenance but with skeptical eyes. Sirius then remembered that it was Sybil Trelawney, the crazy divination teacher that Professor Dumbledore recently hired for upcoming Divination classes. They entered a private room, and Sirius tried to sneak in only to be rebounded backward by an unknown force.

_ It’s not Professor Dumbledore’s memory? _ Sirius scratches his head. Pensieve memory was based on the owner’s past actions and interaction with the environment, which meant that the owner must have not seen the inside. Sirius instead decided to eavesdrop on what he assumed to be an interview. 

_ “Are you a descendant of Cassandra Trelawney, the legendary Seer?”  _ Dumbledore asked.

_ “I am, indeed, _ ” said Sybil pompously.

What ensued was surprisingly dull and disappointing; Dumbledore asked various questions about what Trelawney knew he had in his bag, what objects he kept in his office, and birthdays of his acquaintances, and Sybil got none of them right. It was quite amusing to hear Trelawney’s unwavering confidence, and Sirius assumed that she was just that dense.

He then heard footsteps coming to his direction.

_ Regulus? _ Sirius blinked. Regulus resembled Sirius a lot, though less impressive. The young lad that joined Voldemort out of naïve conviction and hope now looked riddled with exhaustion and fear. Sirius supposed that Regulus had already wanted to bail out at this point.

_ Regulus  _ cast a quick disillusionment spell and went invisible, but Sirius could tell that he was also eavesdropping judging by the quite footsteps. Sirius tried to decipher what came behind the door, but he heard more footsteps.

“Snivellus!” Sirius shouted, unable to suppress his anger. The bat git was definitely here for Voldemort. He leaned against he door, presumably to spy on Dumbledore, but seemed unaware of Regulus’ presence.

“I believe that I need to consider more, Ms. Trelawney,” Sirius quickly focused back to the conversation when he heard Dumbledore’s voice, “I will contact you again within a week after interviewing others-“

“ _ The one with the power to vanquish the Dark Lord approaches _ ,” a hoarse voice croaked.

“I am sorry?” Dumbledore kindly asked.

“ _ Born to those who have thrice defied him _ ,” a voice that was so different from the pretentiously dreamy and mysterious voice continued, “ _ born as the seventh month dies… and the Dark Lord will mark him as his equal, but he will have power the Dark Lord knows not _ …”

_ “What the hell you are doing you bastard!” _

Sirius jolted from the sudden, aggressive voice. A man that resembled Dumbledore but lacked unique smile barked and dragged Snape by his collar. “Get the hell out of here, out! Out!” Snape let out a couple expletives while being dragged away, much to Sirius joy before he quickly focused on Trelawney’s utterance. 

“ _ The conquerors will dispel the Dark Lord, but his unholy existence shall persist _ -“

_ What? _ Sirius thought _ ? Conquerors? Why plural _ ?

“ _ -for only the conquerors’ hearts and blood of the last son of dark constellation shall expel the unholy soul once and for all, or the moon and the sun shall be devoured by an endless abyss _ … _ and either side must die at the hand of the other for neither can live while the other survive… the one with the power to vanquish the Dark Lord will be born as the seventh moon dies _ .”

The unsettling voice stopped, and the memory disintegrated, expelling Sirius out of Pensieve. Sirius panted and shook his head.

“So it was Snape, he was the reason Voldemort targeted them,” he gritted his teeth. Sweat rained on his forehead. It all made sense now – why Voldemort was targeting Harry, and why professor Dumbeldore wanted to hide them under Fidelius. James and Lily did escape from Voldemort’s direct attack three times, and harry was born on July 31 st .

…But what did the  _ dark constellation _ mean **?**

“Master Regulus wanted to read you this,” Kreacher handed a letter with an initial R.A.B. Sirius opened the letter and read the writings of familiar calligraphy.

_ Dear Sirius, _

_ By the time you read this, I assume that Voldemort is most likely ‘dead’, and I am not part of the living world. I know that you deplore my aversion to muggles and fraternization with Death Eaters, and while I do believe that wizards deserve better lives instead of hiding away from muggles, I have concluded that I was wrong to submit myself to such a megalomaniac who wrecks aimless havocs. However, as you know, once I join them, there is no turning back. _

“That’s what you get for being so naïve,” said Sirius, but without his usual disdain to his brother.

_ I could not bear to turn on them until he almost killed Kreacher to hide one of his greatest secrets to his immortality. He boasted many times that he has achieved the states that no wizards ever reached, but I know what he meant. _

“What?!”

“Shh! Mistress might hear!” Kreacher warned.

_ Have you ever heard about Horcrux? It is a piece of object that stores fragments of your soul, anchoring yourself to this realm of world. Even if your original piece dies, as long as your other pieces live, you can always come back, and that is why Voldemort will never die unless all the pieces are destroyed.  _ _ I don’t know how many he has, but it is definitely more than a few. I stole one of them and instructed Kreacher to destroy it by all means. _

“-holy shit,” Sirius panted erratically, “I have to tell professor Dumbledore-“

“Not a chance!” Kreacher summoned ropes and tied down Sirius, “Master Regulus instructed me to not let you go to Dumbledore or any of his cohorts!”

“Why not! I finally know Voldemort’s weakness!”

“Just read the rest of it!”

_ Voldemort does not know anything about the conqueror parts, but I am one hundred percent sure that Potters’ children will be the conquerors.  _

“I guess Regulus died before the July of the last year?”

“…he died on last December,” said Kreacher dejectedly. Sirius’s heart felt stung, and he kept reading the letter.

_ Our names come from the stars. Narcissa and Bellatrix married into other families, , mother’s health is failing miserably, and since I am almost certainly dead by now, who do think will the “blood of dark constellation” come? And whose “beating hearts” will be sacrificed?” _

“Harry,” Sirius trembled. _And that weird baby, _too.

_ I assume those “beating hearts” will come from future Potter children. I know that you would happily and stupidly kill yourself to defeat Voldemort, but would you be willing to let your godchildren die? And even if you don’t to kill them, somebody else who knows the prophecy like Dumbledore- _

“There is no way that Dumbledore will kill Harry!” Sirius angrily slammed the floor.

“- _ will definitely sacrifice them for greater good. You say I am naïve, but when I look at you, I think  _ you _ are also naïve in a different way, idolizing Dumbledore as if he were faultless. At the end of the day, he too is one of the most powerful wizards  _ and _ politicians in the world. I will guarantee you that he will someday try to kill you  _ and _ them. Do you not think it is unfair of him to not share the prophecy with you? I am sure that they told Potters, at least some part of it. I don’t know if you noticed, but Kreacher has been spying on your before I died, and it seemed that neither Dumbledore nor Potters told you about the prophecy. Or, Dumbledore may not have told them the entirety of prophecy out of fear that they may spill the bean to you. By the way, Kreacher only followed my orders, so don’t try to beat him or anything. _

“You were watching me? How?”

“Kreacher or other house-elves can go around wizards’ wards and protection spells,” Kreacher answered.

“I…I never knew.”

_ Therefore, I want to show you that you have two choices. One is that you can run back to Dumbledore like a spineless dog to get yourself and your godchildren killed, another is that you disappear from this world and live with them, hopefully that you will find ways to break or at least delay the prophecies. I don’t know whether it’s possible to annul a prophecy, but it’s not unheard of that prophecies can be ignored. _

_ This is my Slytherin way of attempting to save you, Sirius. Please, do not make a foolish choice and for once, have some self-preservation. _

_ Your dead brother, _

_ Regulus. _

“Kreacher,” Sirius asked, void of apparent emotion, “where is this Horcrux that you have?”

“I cannot give it to you unless you make choices,” Kreacher croaked.

Sirius buried his face in his hands. It hurt that Professor Dumbledore didn’t tell him that the prophecy involved his own life. There was no doubt that Sirius would happily throw away his life for Harry for the same reason that he wanted to be a Secret Keeper at first. However, at the same time, he thought that he at least had some rights to hear some of the prophecy so that he could at least be prepared for it. He wondered if James and Lily knew, too.

_ No way, _ Sirius refused to believe so. Peter’s betrayal rattled him enough already, and to think that his other best friends would sacrifice his life without even consulting him would mean that they didn’t value his life and he did theirs. Perhaps Professor Dumbledore didn’t tell them the full extent out of security concern.

_ Or he really did it because he didn’t trust them to not tell me. _

Doubt started to dig into his heart deeply, and he skimmed Regulus’ letter again. 

.. _ idolizing Dumbledore as if he were faultless. In the end, he too is one of the most powerful wizard  _ and _ politician in the world. I will guarantee you that he will someday try to kill you  _ and _ them… _

Was he really as naïve as Regulus claimed? Suspicion sprouted and spread inside Sirius’ fragile state of mind. Looking back at everything Dumbledore did, Sirius couldn’t help realizing that he was rather secretive, even to his allies. Considering that a number of their comrades were tortured to death to extract information regarding Order of Phoenix, perhaps it would be wise to not every detail to them. However, there were also times that more vocal members like Madeye Moody and Augusta Longbottom complained that Albus kept too much to himself, but Sirius and others wholly trusted Albus to have his reasons.

Sirius leaned against the wall and slowly slouched onto the floor. Whether Dumbledore was evil as Regulus made out or not, he knew one thing for sure.

He would never let anyone hurt Harry- and perhaps his weird “twin - and if it meant going against Dumbledore, he would do it.

“Where is the mother?”

“Mistress is sleeping in her bed. She has been spending more than half a day in her room after Master Regulus disappeared and the Master Orion passed away,” Kreacher’s ears flopped. He then muttered, “…and a bastard son like you breaking her heart.”

“I am sure that she wouldn’t accept me even if I tell her that I am now a Death Eater,” Sirius scoffed, “but I am going to honor my brother’s words.”

“Are you, really?” Kreacher blinked.

“It was partly my fault for trusting Peter, and I was going to take care of Harry anyway in case James and Lily dies…just, not like this,” Sirius stretched his body, “you know, it will be impossible to hide from Professor Dumbledore and the Order if I stay in Britain. I remember watching a muggle movie about this lad who abandoned everything and left to another continent to start a new life. Maybe I can do that, too? But how will I get enough money to do that?”

“Master Regulus left you a key to the Black Vault, so you should get as much money as possible,” said Kreacher, seemingly happy to see that Sirius decided to honor Regulus’ words.

“Great!” Sirius paced back and forth. “Then where exactly should I go? France can work, I know some French. I am smart enough to pick up language, wait, no. He has friend there, Nicholas Flamel. I can’t go anywhere that Dumbledore has contacts. I have to go somewhere that he will never even consider. Oh, I know!” Sirius hit his forehead. “Lily took me and James to a movie theater one time, and there were these people that Lily said came from…Asia? I think she told me these names of countries that none of us knew. Hell, I think NOBODY in Britain knows that those countries even exist, that’s it! Kreacher! I have to go to Asia!”

“And how are you going to do that?” Kreacher looked at Sirius as if he had gone mad, not bothering to ask what the bloody hell ‘Asia’ meant.

“I need some portkeys that can get me out of Britain to France first, it doesn’t have to be a wizard territory! I will need to do the same thing to move to other places couple times to lose anyone pursuing me. Kreacher, you take care of these kids while I go to Knockturn Alley-“

“No, Master. I am going. ”

“Damn it, Kreacher, I am not going to Dumbledore-“

“Kreacher knows that, but I cannot risk you to get caught by anyone!” Kreacher pinched his nose, 

“it is my duty to protect you and those brats until you get to wherever this Asia is. You stay here with them, and I will get whatever you will need to flee here.”

“You would do that for me?” Sirius asked, wide eyed.

“I hate you for breaking my mistress’ heart, but I will do anything that Master Regulus’ wishes,” Kreacher grumpily said.

“Uhm…” Sirius scratched his hair. “Thank you, Kreacher. I have never been good to you, but I owe you a lot this time.”

“ _ Although _ I wish Master Regulus allowed me to kill you,” Kreacher muttered under his breath before apparating out of the room, which Sirius heard but ignored.

Sirius sighed and approached the cribs. Harry, or the one that Sirius thought was asleep in the crib, while the “twin” was awake. He seemed to be disgruntled that he was placed in this old attic with cobwebs and dusts.

“I don’t know what to call you,” said Sirius, hoisting up Not-Harry. Not-Harry stared at Sirius, who stared back. “Where on earth did you come from?”

Not-Harry blinked but let out a high-pitched flatulence.

“Ugh!” Sirius immediately put Not-Harry next to Harry. Not-Harry seemed to faintly smile in a malicious joy. “I don’t know what I expected from a stupid baby,” Sirius muttered.

_ Poof! _

Kreacher returned with an unassuming bag that made odd sounds of rumbling noises.

“You came back much faster than I thought,” said Sirius, impressed.

“The goblin at the bank told me that he had made a pre-arrangement with Master Regulus a while ago, so it was easy. Here, take this,” Kreacher handed a golden card with Gringotts insignia. “This should have about a fifty thousand galleons.”

_ “Fifty-thousands Galleons?” _ Sirius choked. That was about one-fourth of money that his family had in the bank.

“And this bag that Borgin and Burke prepared for the same reason,” Kreacher shoved it to Sirius, “should have ten undetectable portkeys, a tent for three people, three invisibility cloaks, Lumos-resistant darkness powder, ten emergency potion kits, portable Gringotts access portkeys, portable enemy detection alarms, and everything you will need to hide from others. I also bought  _ How to Reducio your Child Rearing Stress  _ for helping with infants and toddlers.”

“You really went above and beyond, huh,” Sirius hung the bag across his shoulder and took the babies on his arms. The bag was surprisingly light thanks to undetectable extension spell, which made it quite easier for Sirius to move around since he was occupied with two babies.

“Do you know where you will go first?”

“Kreacher, can you first apparate us to Dover, then to Fort Calais? Once I get to the Calais, I will be on my own.”

“Mistress will need medication soon. After that, Kreacher will take you there.”

Kreacher left the attic to tend to Walburga. Sirius sighed, overwhelmed by his sudden plan to disappear from the Earth. James and Lily may not have approved of his decision, but he had to protect Harry- and Not-Harry – at all cost. He was going to leave his entire identity behind and fabricate a whole new one for himself and the babies. A totally lunatic scheme.

Kreacher returned in no time and held Sirius hands. “Are you ready, Master?”

“No, but do I have any choice?”

“Essentially, no.”

The quartet disappeared with a poof. 

**Author's Note:**

> So...this is my first ever Sirius-centric and "Sirius is a parent figure" story combined with horcrux theme of my own twist. This is going to be kind of similar to my previous abandoned story, "Viridian King" in that it will be set in Japan(with its own name for its magical counter part) and Harry will have a different name. 
> 
> Enjoy!


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